Blow molded containers are commonly used for holding various products, such as beverages and detergents, due to their light weight and impact resistant nature, and largely because they are economical in manufacture. To make the containers easier to carry, handles are commonly formed with or attached to the containers. By adding a handle to a container, the manufacturing of the containers is made more complex, thereby increasing the overall cost associated with their manufacture.
In particular, when manufacturing a container with a strain-hardenable material, such as polyethylene terephthalate (PET), for example, the ability to incorporate a handle on the container is further complicated. This results from the strain hardening mechanical properties inherent of PET as it is expanded during blow molding. As a result of the strain hardening, it is difficult to form pockets within the container during the blow molding process sized for receipt of a handle. Commonly, attempts to form pockets result in holes being formed during the blow molding process, thereby resulting in scrap. In addition, due to the mechanical properties of strain-hardening materials, it is difficult to form pockets deep enough to provide secure attachment of a handle within the pocket. As such, handles are commonly attached to blow molded containers by incorporating the handle within the blow mold so that the handle becomes attached to the container in the blow molding process. Unfortunately, this complicates the manufacturing process, thereby increasing the manufacturing costs.
A method of reheat blow molding a container includes the step of positioning a preform in a blow mold cavity defined by a pair of mold halves wherein at least one of the mold halves has an opening with an anvil received therein for movement between a first position outside the cavity and a second position at least partially within the cavity. The preform is expanded within the cavity until the preform conforms substantially to the shape of the cavity defined by the mold halves. While expanding the preform, the anvil is moved from its first position to its second position so that the expanding preform forms a continuous wall around the anvil and provides the container with a pocket for receiving a handle therein. Preferably, the pocket within the container is free of holes and of a depth to insure retention of the handle while in use.